The Answer
There are actually three accepted pluralizations of octopus; the English pluralization – octopuses, the Latin pluralization octopi, and the Greek octopodes.
There are actually three accepted pluralizations of octopus; the English pluralization – octopuses, the Latin pluralization octopi, and the Greek octopods.
In English, we frequently will use the pluralization according to the word origin. For example, the Latin word data is the plural of the word datum instead of datums. The singular bacterium is pluralized to bacteria, not bacteriums. Though in each, it would be valid to use the anglicized plural. Be careful not to go over your mobile datums limit! Greek words were pluralized differently from Latin words. For example, criteria is the plural of criterion and octopodes.
Since the word octopus was originally Greek, it seems only logical that its plural form would be octopodes. Similarly, rhinoceros should become rhinocerotes, and stadium should become stadia. However, using these pretentious plural forms for the sake of grammatical purity would be absurd.
Mirriam-Webster notes that “while octopus may ultimately come from Greek it had a stay in New Latin before arriving here”.
So, which should I use?
I think I’m going to start using the form octopodes, but only if I can pronounce as shown below, and bring on the rhinocerotes. You’re pretty safe using both octopuses (particularly in casual conversation) and octopi (in a more scientific context).